This past week, Russia's state-controlled gas company announced it was raising its prices for Ukraine by 81 percent. The country is heavily dependent on Russian gas. Yesterday, Ukraine's interim Prime Minister called the move an act of, quote, economic aggression, and threatened to sue. It's the latest example of tension between the two countries, which have long shared strong ethnic, linguistic and religious ties. But it seems the latest crisis is forcing Ukrainians to assert their own separate national identity. NPR's Eleanor Beardsley was in the Ukrainian capital of Kiev and has the story.

ELEANOR BEARDSLEY, BYLINE: Long before there was the Soviet Union or Russia, there was Kievan Rus - a federation grouping the Slavic peoples of modern day Russia, Ukraine and Belarus. Kievan Rus thrived from the 9th to the 12th centuries, its capital was Kiev. In 988, Kievan Rus Prince Vladimir I converted the nation to Orthodox Christianity. Kiev Saint Sofia Cathedra was built in 1011. Today, its golden cupolas and crosses still reach towards the sky.

NATALIA: Yes, OK. Now I will show you the interior of the cathedral.

BEARDSLEY: Natalia (ph), who didn't want to give her last name, is a guide at Saint Sophia. She says Kiev is called the mother of Russian cities because it is the oldest, founded in the 5th century. She points out that Moscow was founded 700 years later.

(SOUNDBITE OF SPEECH)

PRESIDENT VLADIMIR PUTIN: (Russian Spoken).

BEARDSLEY: Russian President Vladimir Putin spoke of mother city Kiev and Vladimir the Baptizer in his speech justifying Russia's annexation of Crimea. Natalia says Putin infers that Ukraine is just a part of Russia and not a separate country, and that makes her angry.

NATALIA: I want to say that we have some common pages in history with Russia, but it doesn't mean that must go back to that remote past and be the same together because we are older than Russians. We consider ourselves to be independent.

BEARDSLEY: The tensions with Russia are making many Ukrainians still more Ukrainian than ever. Vlada Osmack (ph) is a university professor. She also moonlights as a guide for Russian tourists. She says Kiev is a powerful symbol for Russians.

VLADA OSMACK: The idea they come here is that Kiev is the root of a Russian culture. Kiev is the root of Russia, which means - and that only surprised me - they think that because of being a root, from their point of view it should belong to them.

BEARDSLEY: Osmack says because Ukraine lies at the crossroads of Europe, it has historically been part of other empires and nations yet it always managed to hang onto its own identity. She says Ukraine gained its independence without a fight when the Soviet Union broke up in 1991. But today, Osmack says Ukrainians are fighting for their nation. In Kiev these days Ukrainian pride is in full display. The country's national anthem is sung day and night in Maidan Square and there are celebrations across the country to mark the 200th anniversary of the birth of Ukraine's national poet Taras Shevchenko. Ironically, Putin is making Ukraine stronger says teacher Igor Sebolieve (ph).

IGOR SEBOLIEVE: Mr. Putin right now is uniting us. This situation started as a movement for Euro integration, then we have a revolution for - against the dictatorship, yes. And now we have really a war for independence of our country.

BEARDSLEY: There's been some nostalgia for a return to Soviet times in Russian-speaking Crimea. But in other parts of Ukraine, there have been attacks on statues of Lenin and other Soviet symbols. I'm down in the Kiev metro. And here at Lenin's gate - the former Lenin's gates - got a new name now - there's a big plywood wall. Behind it is a baralief (ph) of Lenin. They've blocked it up, they've sealed it off so it can't be destroyed. And I just wanted to see if people think it should be here or not.

ALEKSEI OSATRA: (Foreign language spoken).

BEARDSLEY: 26-year-old engineer Aleksei Osatra (ph) says definitely not. Lenin doesn't reflect Ukrainian values, he says. And a lot of Ukrainians were murdered by the communist. I ask him if Ukrainians weren't communist themselves. No, he says, Bolshevism is not part of Ukrainian history, it came from abroad from Russia.

TATYANA ORLOVA: (Foreign language spoken).

BEARDSLEY: 54-year-old Tatyana Orlova (ph) who works with the culture ministry says she holds nothing against the Russian people because they're so ill-informed. It's that devil Putin, she says. Orlova says the Metro station wouldn't lose anything by getting rid of the baralief (ph). But shouldn't history be preserved, I ask her?

ORLOVA: (Foreign language spoken).

BEARDSLEY: Oh, all right, she concedes. But it should stay boarded up for now. When the crisis is over and things have calmed, then we can decide what to do with Lenin. Eleanor Beardsley, NPR news.